Faculty Profiles - FUJITA, Koji

Papers - FUJITA, Koji

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Increasing dust emission from ice free terrain in southeastern Greenland since 2000 Reviewed International journal

Tomomi Amino, Yoshinori Iizuka, Sumito Matoba, Rigen Shimada, Naga Oshima, Toshitaka Suzuki, Takuto Ando, Teruo Aoki, Koji Fujita

Polar Science Vol. 27 page： 100599 - 100599 2021.3

青木輝夫, 的場澄人, 庭野匡思, 朽木勝幸, 谷川朋範, 竹内望, 山口悟, 本山秀明, 藤田耕史, 山崎哲秀, 飯塚芳徳, 堀雅裕, 島田利元, 植竹淳, 永塚尚子, 大沼友貴彦, 橋本明弘, 石元裕史, 田中泰宙, 大島長, 梶野瑞王, 足立光司, 黒﨑豊, 杉山慎, 津滝俊, 東久美子, 八久保晶弘, 川上薫, 木名瀨健

雪氷 : journal of the Japanese Society of Snow and Ice Vol. 83 ( 2 ) page： 169 - 191 2021.3

氷床表面質量収支の実態とそのモデリングの試み：2020年夏最新版. Reviewed

庭野匡思, 青木輝夫, 橋本明弘, 大島長, 梶野瑞王, 大沼友貴彦, 藤田耕史, 山口悟, 島田利元, 竹内望, 津滝俊, 本山秀明, 石井正好, 杉山慎, 平沢尚彦, 阿部彩子

雪氷 Vol. 83 ( 1 ) page： 27 - 50 2021.1

Review of the current polar ice sheet surface mass balance and its modelling: the 2020 summer edition

庭野匡思, 青木輝夫, 青木輝夫, 橋本明弘, 大島長, 梶野瑞王, 大沼友貴彦, 藤田耕史, 山口悟, 島田利元, 竹内望, 津滝俊, 津滝俊, 本山秀明, 石井正好, 杉山慎, 平沢尚彦, 阿部彩子, 阿部彩子

雪氷 Vol. 83 ( 1 ) 2021

Ice Core Drilling and the Related Observations at SE-Dome site, southeastern Greenland Ice Sheet Reviewed

Yoshinori IIZUKA, Sumito MATOBA, Masahiro MINOWA, Tetsuhide YAMASAKI, Kaoru KAWAKAMI, Ayako KAKUGO, Morihiro MIYAHARA, Akihiro HASHIMOTO, Masashi NIWANO, Tomonori TANIKAWA, Koji FUJITA, Teruo AOKI

Bulletin of Glaciological Research Vol. 39 page： 1 - 12 2021

The Second Deep Ice Coring at Dome Fuji, Antarctica Reviewed International coauthorship

Antarctic Record Vol. 64 ( 64 ) page： 284 - 329 2020.12

GrSMBMIP: intercomparison of the modelled 1980–2012 surface mass balance over the Greenland Ice Sheet Reviewed International coauthorship International journal

Xavier Fettweis, Stefan Hofer, Uta Krebs-Kanzow, Charles Amory, Teruo Aoki, Constantijn J. Berends, Andreas Born, Jason E. Box, Alison Delhasse, Koji Fujita, Paul Gierz, Heiko Goelzer, Edward Hanna, Akihiro Hashimoto, Philippe Huybrechts, Marie-Luise Kapsch, Michalea D. King, Christoph Kittel, Charlotte Lang, Peter L. Langen, Jan T. M. Lenaerts, Glen E. Liston, Gerrit Lohmann, Sebastian H. Mernild, Uwe Mikolajewicz, Kameswarrao Modali, Ruth H. Mottram, Masashi Niwano, Brice Noël, Jonathan C. Ryan, Amy Smith, Jan Streffing, Marco Tedesco, Willem Jan van de Berg, Michiel van den Broeke, Roderik S. W. van de Wal, Leo van Kampenhout, David Wilton, Bert Wouters, Florian Ziemen, Tobias Zolles

The Cryosphere Vol. 14 ( 11 ) page： 3935 - 3958 2020.11

Language：English Publishing type：Research paper (scientific journal) Publisher：Copernicus GmbH

Abstract. Observations and models agree that the Greenland Ice Sheet (GrIS)
surface mass balance (SMB) has decreased since the end of the 1990s due to
an increase in meltwater runoff and that this trend will accelerate in the
future. However, large uncertainties remain, partly due to different
approaches for modelling the GrIS SMB, which have to weigh physical
complexity or low computing time, different spatial and temporal
resolutions, different forcing fields, and different ice sheet
topographies and extents, which collectively make an inter-comparison
difficult. Our GrIS SMB model intercomparison project (GrSMBMIP) aims to
refine these uncertainties by intercomparing 13 models of four types which
were forced with the same ERA-Interim reanalysis forcing fields, except for
two global models. We interpolate all modelled SMB fields onto a common ice
sheet mask at 1 km horizontal resolution for the period 1980–2012 and score
the outputs against (1) SMB estimates from a combination of gravimetric
remote sensing data from GRACE and measured ice discharge; (2) ice cores,
snow pits and in situ SMB observations; and (3) remotely sensed bare ice extent
from MODerate-resolution Imaging Spectroradiometer (MODIS). Spatially, the
largest spread among models can be found around the margins of the ice
sheet, highlighting model deficiencies in an accurate representation of the
GrIS ablation zone extent and processes related to surface melt and runoff.
Overall, polar regional climate models (RCMs) perform the best compared to
observations, in particular for simulating precipitation patterns. However,
other simpler and faster models have biases of the same order as RCMs
compared with observations and therefore remain useful tools for long-term
simulations or coupling with ice sheet models. Finally, it is interesting to
note that the ensemble mean of the 13 models produces the best estimate of
the present-day SMB relative to observations, suggesting that biases are not
systematic among models and that this ensemble estimate can be used as a
reference for current climate when carrying out future model developments.
However, a higher density of in situ SMB observations is required,
especially in the south-east accumulation zone, where the model spread can
reach 2 m w.e. yr−1 due to large discrepancies in modelled snowfall accumulation.

DOI： 10.5194/tc-14-3935-2020

Web of Science

Partitioning the Uncertainty of Ensemble Projections of Global Glacier Mass Change Reviewed International coauthorship International journal

Ben Marzeion, Regine Hock, Brian Anderson, Andrew Bliss, Nicolas Champollion, Koji Fujita, Matthias Huss, Walter W. Immerzeel, Philip Kraaijenbrink, Jan‐Hendrik Malles, Fabien Maussion, Valentina Radić, David R. Rounce, Akiko Sakai, Sarah Shannon, Roderik Wal, Harry Zekollari

Earth's Future Vol. 8 ( 7 ) page： e2019EF001470 2020.7

The influence of water percolation through crevasses on the thermal regime of a Himalayan mountain glacier Reviewed International coauthorship International journal

Adrien Gilbert, Anna Sinisalo, Tika R. Gurung, Koji Fujita, Sudan B. Maharjan, Tenzing C. Sherpa, Takehiro Fukuda

The Cryosphere Vol. 14 ( 4 ) page： 1273 - 1288 2020.4

Language：English Publishing type：Research paper (scientific journal) Publisher：Copernicus GmbH

Abstract. In cold and arid climates, small glaciers with cold accumulation
zones are often thought to be entirely cold based. However, scattering in
ground-penetrating radar (GPR) measurements on the Rikha Samba Glacier in
the Nepal Himalayas suggests a large amount of temperate ice that seems to
be influenced by the presence of crevassed areas. We used a coupled
thermo-mechanical model forced by a firn model accounting for firn heating
to interpret the observed thermal regime. Using a simple energy conservation
approach, we show that the addition of water percolation and refreezing in
crevassed areas explains these observations. Model experiments show that
both steady and transient thermal regimes are significantly affected by
latent heat release in crevassed areas. This makes half of the glacier base
temperate, resulting in an ice dynamic mainly controlled by basal friction
instead of ice deformation. The timescale of thermal regime change, in
response to atmospheric warming, is also greatly diminished, with a
potential switch from cold to temperate basal ice in 50–60 years in the
upper part of the glacier instead of the 100–150 years that it would take
without the effect of the crevasses. This study highlights the crucial role
of water percolation through the crevasses on the thermal regime of glaciers
and validates a simple method to account for it in glacier thermo-mechanical
models.

DOI： 10.5194/tc-14-1273-2020

Web of Science

Contrasting thinning patterns between lake- and land-terminating glaciers in the Bhutanese Himalaya Reviewed International coauthorship International journal Open Access

Tsutaki, Shun, Fujita, Koji, Nuimura, Takayuki, Sakai, Akiko, Sugiyama, Shin, Komori, Jiro, Tshering, Phuntsho

CRYOSPHERE Vol. 13 ( 10 ) page： 2733 - 2750 2019.10

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：COPERNICUS GESELLSCHAFT MBH

Despite the importance of glacial lake development in ice dynamics and glacier thinning, in situ and satellite-based measurements from lake-terminating glaciers are sparse in the Bhutanese Himalaya, where a number of proglacial lakes exist. We acquired in situ and satellite-based observations across lake- and land-terminating debris-covered glaciers in the Lunana region, Bhutanese Himalaya. A repeated differential global positioning system survey reveals that thickness change of the debris-covered ablation area of the lake-terminating Lugge Glacier (-4.67 +/- 0.07 m a(-1)) is more than 3 times more negative than that of the land-terminating Thorthormi Glacier (-1 40 +/- 0.07 m a(-1)) for the 2004-2011 period. The surface flow velocities decrease down-glacier along Thorthormi Glacier, whereas they increase from the upper part of the ablation area to the terminus of Lugge Glacier. Numerical experiments using a two-dimensional ice flow model demonstrate that the rapid thinning of Lugge Glacier is driven by both a negative surface mass balance and dynamically induced ice thinning. However, the thinning of Thorthormi Glacier is minimised by a longitudinally compressive flow regime. Multiple supraglacial ponds on Thorthormi Glacier have been expanding since 2000 and have merged into a single proglacial lake, with the glacier terminus detaching from its terminal moraine in 2011. Numerical experiments suggest that the thinning of Thorthormi Glacier will accelerate with continued proglacial lake development.

DOI： 10.5194/tc-13-2733-2019

Open Access

Web of Science

Mass balance of Trambau Glacier, Rolwaling region, Nepal Himalaya: in-situ observations, long-term reconstruction and mass-balance sensitivity Reviewed International coauthorship International journal Open Access

Sunako, Sojiro, Fujita, Koji, Sakai, Akiko, Kayastha, Rijan B.

JOURNAL OF GLACIOLOGY Vol. 65 ( 252 ) page： 605 - 616 2019.8

Language：English Publishing type：Research paper (scientific journal) Publisher：CAMBRIDGE UNIV PRESS

We conducted a mass-balance study of debris-free Trambau Glacier in the Rolwaling region, Nepal Himalaya, which is accessible to 6000 m a.s.l., to better understand mass-balance processes and the effect of precipitation on these processes on high-elevation Himalayan glaciers. Continuous in situ meteorological and mass-balance observations that spanned the three melt seasons from May 2016 are reported. An energy- and mass-balance model is also applied to evaluate its performance and sensitivity to various climatic conditions. Glacier-wide mass balances ranging from -0.34 +/- 0.38 m w.e. in 2016 to -0.82 +/- 0.53 m w.e. in 2017/18 are obtained by combining the observations with model results for the areas above the highest stake. The estimated long-term glacier mass balance, which is reconstructed using the ERA-Interim data calibrated with in situ data, is -0.65 +/- 0.39 m w.e. a(-1) for the 1980-2018 period. A significant correlation with annual precipitation (r = 0.77, p < 0.001) is observed, whereas there is no discernible correlation with summer mean air temperature. The results indicate the continuous mass loss of Trambau Glacier over the last four decades, which contrasts with the neighbouring Mera Glacier in balance.

DOI： 10.1017/jog.2019.37

Open Access

Web of Science

Reduced marine phytoplankton sulphur emissions in the Southern Ocean during the past seven glacials Reviewed International journal Open Access

Goto-Azuma K, Hirabayashi M, Motoyama H, Miyake T, Kuramoto T, Uemura R, Igarashi M, Iizuka Y, Sakurai T, Horikawa S, Suzuki K, Suzuki T, Fujita K, Kondo Y, Hattori S, Fujii Y

Nature Communications Vol. 10 ( 1 ) page： 324 2019.7

Language：English Publishing type：Research paper (scientific journal)

© 2019, The Author(s). Marine biogenic sulphur affects Earth’s radiation budget and may be an indicator of primary productivity in the Southern Ocean, which is closely related to atmospheric CO2 variability through the biological pump. Previous ice-core studies in Antarctica show little climate dependence of marine biogenic sulphur emissions and hence primary productivity, contradictory to marine sediment records. Here we present new 720,000-year ice core records from Dome Fuji in East Antarctica and show that a large portion of non-sea-salt sulphate, which was traditionally used as a proxy for marine biogenic sulphate, likely originates from terrestrial dust during glacials. By correcting for this, we make a revised calculation of biogenic sulphate and find that its flux is reduced in glacial periods. Our results suggest reduced dimethylsulphide emissions in the Antarctic Zone of the Southern Ocean during glacials and provide new evidence for the coupling between climate and the Southern Ocean sulphur cycle.

DOI： 10.1038/s41467-019-11128-6

Influence of summer sublimation on δD, δ<sup>18</sup>O and δ<sup>17</sup>O in precipitation, East Antarctica, and implications for climate reconstruction from ice cores Reviewed International coauthorship International journal

Pang HX, Hou SG, Landais A, Masson-Delmotte V, Jouzel J, Steen-Larsen HC, Risi C, Zhang WB, Wu SY, Li YS, An CL, Wang YT, Prie F, Minster B, Falourd S, Stenni B, Scarchilli C, Fujita K, Grigioni P

Journal of Geophysical Research: Atmospheres Vol. 124 ( 13 ) page： 7339 - 7358 2019.7

Viscoelastic modeling of nocturnal thermal fracturing in a Himalayan debris-covered glacier Reviewed International coauthorship International journal

Podolskiy EA, Fujita K, Sunako S, Sato Y

Journal of Geophysical Research: Earth Surface Vol. 124 ( 6 ) page： 1485 - 1515 2019.6

Simulations of black carbon (BC) aerosol impact over Hindu Kush Himalayan sites: validation, sources, and implications on glacier runoff Reviewed International coauthorship

Santra S, Verma S, Fujita K, Chakraborty I, Boucher O, Takemura T, Burkhart JF, Matt F, Sharma M

Atmospheric Chemistry and Physics Vol. 19 ( 4 ) page： 2441 - 2460 2019.2

Assessment for paleoclimatic utility of biomass burning tracers in SE-Dome ice core, Greenland Reviewed International coauthorship Open Access

Fahmida Parvin, Osamu Seki, Koji Fujita, Yoshinori Iizuka, Sumito Matoba, Takuto Ando, Ken Sawada

Atmospheric Environment Vol. 196 page： 86 - 94 2019.1

Language：English Publishing type：Research paper (scientific journal)

© 2018 The Authors We provide continuous records of biomass burning molecular tracers (levoglucosan and dehydroabietic acid) in a Greenland ice core collected from the Southeastern Dome (the SE-Dome ice core) over the past several decades to assess the paleoclimatic utility of these tracers in Greenland ice cores. An air mass backward-trajectory analysis indicates that eastern Canada is likely the primary source region of the biomass burning tracers. Comparisons of levoglucosan and dehydroabietic acid data in the SE-Dome ice core and area burned (vegetation fire) events in Canada suggests that the biomass burning tracers in the ice core document most of the pronounced biomass burning events in eastern Canada over the past several decades, confirming that analyses of biomass burning molecular tracers in Greenland ice cores are useful to reconstruct the frequency of significant biomass burning events in a local region. However, our study also highlights that the wind pattern when the biomass burning occurs is decisive for the registration of a biomass burning event in an ice core even though long-term changes in the wind regime associated with decadal-scale climate oscillations do not significantly influence the transport and deposition of biomass burning tracers on the Greenland ice sheet.

DOI： 10.1016/j.atmosenv.2018.10.012

Open Access

Web of Science

Scopus

Annual layer counting using pollen grains of the Grigoriev ice core from the Tien Shan Mountains, central Asia Reviewed International coauthorship International journal Open Access

Takeuchi N, Sera S, Fujita K, Aizen VB, Kubota J

Arctic, Antarctic, and Alpine Research Vol. 51 ( 1 ) page： 299 - 312 2019

Language：English Publishing type：Research paper (scientific journal)

Pollen grains are commonly found in ice cores, particularly those from mountain glaciers at low to middle latitudes. Because the release of pollen from flowers has a seasonality and varies among the plant species, pollen concentrations in ice cores are useful for distinguishing annual or seasonal layers and inferring past vegetation near glaciers. We analyzed major pollen grains in an 87-m-deep ice core drilled at the top of the Grigoriev Ice Cap (4563 m.a.s.l.) in the Tien Shan Mountains, Kyrgyz Republic. Microscopy showed that mainly five pollen taxa were contained in the ice core. Their abundance fluctuated with the depth of the core, indicating their seasonal deposition on the ice cap, while the seasonality of the stable isotopes was not particularly clear because of melting and refreezing signatures. Based on the pollen profiles, annual layers were determined back in time to 1780 AD at a depth of 63.6 m; at greater depth, they could not be distinguished due to ice layer thinning in the glacier. The pollen assemblages have gradually changed during the last 220 years and were particularly distinctive in the deeper part, suggesting the drastic change of vegetation in this region during the Holocene.

DOI： 10.1080/15230430.2019.1638202

Open Access

Web of Science

Scopus

Status and Change of the Cryosphere in the Extended Hindu Kush Himalaya Region Invited Reviewed International coauthorship

Bolch Tobias, Shea Joseph M., Liu Shiyin, Azam Farooq M., Gao Yang, Gruber Stephan, Immerzeel Walter W., Kulkarni Anil, Li Huilin, Tahir Adnan A., Zhang Guoqing, Zhang Yinsheng, Bannerjee Argha, Berthier Etienne, Brun Fanny, Kaab Andreas, Kraaijenbrink Phillip, Moholdt Geir, Nicholson Lindsey, Pepin Nicholas, Racoviteanu Adina, Fujita Koji

HINDU KUSH HIMALAYA ASSESSMENT: MOUNTAINS, CLIMATE CHANGE, SUSTAINABILITY AND PEOPLE page： 209 - 255 2019

Nocturnal thermal fracturing of a Himalayan debris-covered glacier revealed by ambient seismic noise Reviewed International coauthorship

Podolskiy EA, Fujita K, Sunako S, Tsushima A, Kayastha RB

Geophysical Research Letters Vol. 45 ( 18 ) page： 9699 - 9709 2018.9

Demographic analysis of cyanobacteria based on the mutation rates estimated from an ancient ice core Reviewed International coauthorship Open Access

Takahiro Segawa, Nozomu Takeuchi, Koji Fujita, Vladimir B. Aizen, Eske Willerslev, Takahiro Yonezawa

Heredity Vol. 120 ( 6 ) page： 562 - 573 2018.6

Language：English Publishing type：Research paper (scientific journal) Publisher：Nature Publishing Group

Despite the crucial role of cyanobacteria in various ecosystems, little is known about their evolutionary histories, especially microevolutionary dynamics, because of the lack of knowledge regarding their mutation rates. Here we directly estimated cyanobacterial mutation rates based on ancient DNA analyses of ice core samples collected from Kyrgyz Republic that dates back to ~12,500 cal years before present. We successfully sequenced the 16S rRNA and 16S-23S internal transcribed spacer (ITS) region. Two cyanobacterial operational taxonomic units (OTUs) were detected from the ancient ice core samples, and these OTUs are shared with those from the modern glacier surface. The mutation rate of ITS region was estimated by comparing ancient and modern populations, and were at the magnitude of 10-7substitutions/sites/year. By using a model selection framework, we also demonstrated that the ancient sequences from the ice sample were not contaminated from modern samples. Bayesian demographic analysis based on coalescent theory revealed that cyanobacterial population sizes increased over Asia regions during the Holocene. Thus, our results enhance our understanding of the enigmatic timescale of cyanobacterial microevolution, which has the potential to elucidate the environmental responses of cyanobacteria to the drastic climatic change events of the Quaternary.

DOI： 10.1038/s41437-017-0040-3

Web of Science

Scopus

PubMed

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Papers - FUJITA, Koji